Energy storage device



FIG. 1 is a top perspective view of an energy storage device of the present invention;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a second side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof. 

We claim the ornamental design for an energy storage device, as shown and described. 